From: Matt S Trout <mst@shadowcat.co.uk>
Date: Mon, 16 Apr 2018 02:38:01 +0000 (+0000)
Subject: show dependencies before backtracking
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=4db57c0455eccf4cb7ac0b89abdc1969add73685;p=scpubgit%2FDX.git

show dependencies before backtracking
---

diff --git a/fragment.output/btdemo b/fragment.output/btdemo
index f42caa6..33df4d0 100644
--- a/fragment.output/btdemo
+++ b/fragment.output/btdemo
@@ -126,10 +126,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 remaining resolution_space {
     proposition member_at Y ?YKey ?YValue
     geometry_depends_on { INDICES_OF 0.Y; TYPE_OF 0.YKey; TYPE_OF 0.YValue }
@@ -184,10 +184,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 remaining resolution_space {
     proposition member_at Y ?YKey ?YValue
     geometry_depends_on { INDICES_OF 0.Y; TYPE_OF 0.YKey; TYPE_OF 0.YValue }
@@ -239,10 +239,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 remaining resolution_space {
     proposition member_at X ?XKey ?XValue
     geometry_depends_on { INDICES_OF 0.X; TYPE_OF 0.XKey; TYPE_OF 0.XValue }
@@ -328,10 +328,10 @@ recheck eq ?Y {{ d 1 e 2 f 3 }} {
         actions { SetValue 0.Y {{ d 1 e 2 f 3 }} }
         depends_on { CONTENTS_OF 0.Y }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.Y }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.YValue }
 remaining resolution_space {
     proposition member_at Y ?YKey ?YValue
     geometry_depends_on { INDICES_OF 0.Y; TYPE_OF 0.YKey; TYPE_OF 0.YValue }
@@ -429,10 +429,10 @@ recheck eq ?Y {{ d 1 e 2 f 3 }} {
         actions { SetValue 0.Y {{ d 1 e 2 f 3 }} }
         depends_on { CONTENTS_OF 0.Y }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.Y }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.YValue }
 remaining resolution_space {
     proposition member_at X ?XKey ?XValue
     geometry_depends_on { INDICES_OF 0.X; TYPE_OF 0.XKey; TYPE_OF 0.XValue }
@@ -505,10 +505,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 remaining resolution_space {
     proposition member_at Y ?YKey ?YValue
     geometry_depends_on { INDICES_OF 0.Y; TYPE_OF 0.YKey; TYPE_OF 0.YValue }
@@ -563,10 +563,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 remaining resolution_space {
     proposition member_at Y ?YKey ?YValue
     geometry_depends_on { INDICES_OF 0.Y; TYPE_OF 0.YKey; TYPE_OF 0.YValue }
@@ -618,10 +618,10 @@ recheck eq ?X {{ a 1 b 2 c 3 }} {
         actions { SetValue 0.X {{ a 1 b 2 c 3 }} }
         depends_on { CONTENTS_OF 0.X }
     }
-    backtrack
+    backtrack because { CONTENTS_OF 0.X }
     fail_recheck
 }
-backtrack
+backtrack because { CONTENTS_OF 0.XValue }
 {{
     X {{ a 1 b 2 c 3 }}
     XKey 'b'
diff --git a/lib/DX/Step/Backtrack.pm b/lib/DX/Step/Backtrack.pm
index 9a92677..06d1986 100644
--- a/lib/DX/Step/Backtrack.pm
+++ b/lib/DX/Step/Backtrack.pm
@@ -1,16 +1,33 @@
 package DX::Step::Backtrack;
 
+use DX::DependencyMap;
+use DX::Utils qw(format_deps);
 use DX::Class;
 
 with 'DX::Role::Step';
 
-#has resolution_space => (is => 'ro', isa => ResolutionSpace, required => 1);
+has resolution_space => (is => 'ro', isa => ResolutionSpace, required => 1);
 
 sub apply_to {
   my ($self, $ss) = @_;
-  trace backtrack => [ statement => [ [ symbol => 'backtrack' ] ] ];
+  my $rspace = $self->resolution_space;
+  trace backtrack => [ statement => [
+    [ symbol => 'backtrack' ],
+    [ statement => [
+      [ symbol => 'because' ],
+      format_deps($rspace->geometry_depends_on)
+    ] ]
+  ] ];
+  my $dmap = DX::DependencyMap->new_empty
+                              ->with_dependencies_for(
+                                  backtrack => $rspace->geometry_depends_on
+                                );
+
   foreach my $adj (@{$ss->decisions_taken}) {
     my ($rspace_was, $ss_was) = @$adj;
+    $dmap = $dmap->with_dependencies_for(
+      backtrack => $rspace_was->geometry_depends_on
+    );
     next unless @{$rspace_was->remaining_resolution_space->members};
     trace rspace => [ statement => [
       [ symbol => 'remaining' ],
diff --git a/lib/DX/Utils.pm b/lib/DX/Utils.pm
index b52119d..2bef078 100644
--- a/lib/DX/Utils.pm
+++ b/lib/DX/Utils.pm
@@ -11,7 +11,7 @@ my @const = (
 our @EXPORT_OK = (
   @const,
   (my @builders = qw(rspace rstrat res string number dict proposition)),
-  'deparse', '*trace', 'expand_deps',
+  'deparse', '*trace', 'expand_deps', 'format_deps',
 );
 
 our %EXPORT_TAGS = (
@@ -56,6 +56,15 @@ sub expand_deps {
   [ map _expand_dep($_), @{$_[0]} ]
 }
 
+sub format_deps {
+  [ block => [
+      map [ statement => [
+        [ symbol => (split '::', ${$_->[0]})[-1] ],
+        [ value_path => [ @{$_}[1..$#$_] ] ]
+      ] ], @{$_[0]}
+  ] ]
+}
+
 sub rspace {
   require DX::ResolutionSpace;
   DX::ResolutionSpace->new(@_);